I understood that cat's can't metabolize plant oils. If that is the case, then is lecithin in cat food contraindicated?
We have not seen any scientific or empirical evidence of such claims. Wysong has used plant oils in its products fed to hundreds of thousands of animals through multiple generations for the past 35 years, with health, not disease resulting. Some Wysong cats are now in their late twenties! Please see the Wysong monograph regarding nutritious oils: http://www.wysong.net/products/documents/monographs/legacy/EFA.pdf.
You might also find the following Dr. Wysong books regarding lipids, oils, and fats of interest: